JP2022011691A - Porous ceramic heat generating body - Google Patents

Abstract

To provide a porous ceramic heat generating body which can provide high evaporation efficiency and high durability performance when evaporating atomized liquid.SOLUTION: In a porous ceramic heat generating body 10, a porous ceramic substrate 12 does not require conductivity, such that there is no limitation in material, and material selectivity of the substrate is high, such that chemical resistance with respect to an atomized liquid is made compatible with a mechanical strength by selecting a porous ceramic substrate material according to the application. A resistor pattern 18 is fixed to a heating face 12a which is one face of the porous ceramic substrate 12 having a porosity/flexion degree coefficient ratio of 21 or more, via a glass layer 16 formed in at least a partial region including the resistor pattern 18 in the heating face 12a, thereby obtaining heat shock resistance and an adhesive strength of the resistor pattern 18 which is functioned as an electro-resistive heat generating body. Thus, the porous ceramic heat generating body 10 can provide high evaporation efficiency and high durability performance.SELECTED DRAWING: Figure 1

Description

Regarding a porous ceramic heating element in which a resistor pattern and a pair of electrode patterns overlapping the resistor pattern are fixed on one surface of a porous ceramic substrate, in particular, atomization of an atomized liquid infiltrated into the porous ceramic substrate. In connection with a technique for improving the evaporation efficiency and durability of a porous ceramic substrate in use for.

Ceramic heating elements are used in various applications such as sensors, atomizers for humidity control, and heating devices for substance synthesis. For example, in Patent Document 1, in a ceramic heater in which a resistance heating element and a lead wire are embedded inside an insulating ceramic substrate, durability performance is improved by optimizing the material and film thickness of the resistance heating element and the lead wire. Has been proposed. However, in a heater using a dense ceramic substrate, it is difficult to continuously supply the atomized liquid when the purpose is to evaporate the atomized liquid, and good evaporation efficiency cannot be obtained.

Japanese Unexamined Patent Publication No. 2000-340349 Japanese Patent No. 5685152

On the other hand, in order to obtain good evaporation efficiency, a porous body is used as a substrate or a heating element, and the atomized liquid is directly and continuously supplied to the heating part by a capillary phenomenon to infiltrate the porous body. Proposed ones that allow the chemical liquid to evaporate quickly. For example, it is the porous heating element described in Patent Document 2. According to this porous heating element, the porous body itself is an electric resistance heating element that generates heat, and since it is composed of a porous body made mainly of aluminum, it has good mechanical strength and energization heat generation. Has been done.

However, according to the above-mentioned porous heating element, the porous body itself must be a conductive substance, and particularly when it is used for the purpose of evaporating a liquid, it has chemical resistance and mechanical strength against a liquid depending on the application. There was a problem that it was difficult to achieve both.

It is also conceivable to form a heating element on one surface of an insulating porous body such as ceramics, but in this case, multiple types of ceramic materials can be used for the porous body, and the material selectivity of the substrate is high. However, since the electric resistance heating element formed on the uneven surface of the porous body is not uniform in thickness and locally differs, there is a problem that the thermal impact resistance is low and the adhesive strength between the substrate and the electric resistance heating element is also low. there were.

The present invention has been made in the background of the above circumstances, and an object thereof is to provide a porous ceramic heating element that can obtain high evaporation efficiency and durability when used for the purpose of evaporating a liquid. To do.

Against the background of the above circumstances, the present inventors have conducted various studies on a porous ceramic heating element for liquid atomization, and as a result, a resistor pattern and a resistance pattern thereof are overlapped on one surface of the porous ceramic substrate. When the pair of electrode patterns are fixed via a glass layer formed in at least a part of one surface of the porous ceramic substrate including the resistance pattern, the substrate selectivity is wide and electric resistance heat generation is generated. We have found the fact that a porous ceramic heating element with thermal impact resistance and adhesive strength of the body and evaporation efficiency and durability can be obtained. The present invention has been made based on such findings.

That is, the gist of the first invention is that (a) a resistor pattern and a pair of electrode patterns overlapping the resistor pattern are fixed on one surface of a porous ceramic substrate, and between the pair of electrode patterns. It is a porous ceramic heating element that generates heat by supplying an electric current to the porous ceramic substrate, wherein (b) the pore ratio bending degree coefficient ratio of the porous ceramic substrate is 21 or more, and (c) the porous. A glass layer is fixed to at least a part of one surface of the quality ceramic substrate including the resistor pattern, and the resistor pattern is fixed on the glass layer. (D) The porous ceramic. The purpose is to atomize the atomized liquid that has penetrated into the substrate from one surface of the porous ceramic substrate that is not covered by the glass layer by heating the resistor pattern.

According to the first invention, the porosity bending degree coefficient ratio of the porous ceramic substrate is 21 or more, and one surface of the porous ceramic substrate contains at least the resistance pattern of the other surface. Since the resistor pattern is fixed via the glass layer formed in a part of the region, the thermal impact resistance and the adhesive strength of the electric resistance heating element can be obtained, and high durability performance can be obtained. Further, since the atomized liquid that has penetrated into the porous ceramic substrate is atomized by heating by the resistor pattern, high evaporation efficiency can be obtained.

Here, preferably, the porosity bending degree coefficient ratio of the porous ceramic substrate is 26 or more. As a result, the porous ceramic heating element is provided with pores having a high porosity and small bending, so that high atomization performance can be obtained. If the porosity bending degree coefficient ratio is less than 26, the porosity may be too low or the pores may be bent too much, resulting in insufficient infiltration of the atomized liquid, and sufficient atomization performance can be obtained. It becomes difficult.

Further, preferably, the porous ceramic substrate has an average porosity of 40 to 71% by volume. This facilitates the infiltration of the atomized liquid into the porous ceramic substrate, so that the evaporation efficiency of the atomized liquid, that is, the atomization performance is improved. If the porosity exceeds 71% by volume, it becomes difficult to sufficiently obtain the durability of the porous ceramic heating element due to the peeling of the glass layer, the resistor pattern, or the electrode pattern. If the porosity is less than 40% by volume, it becomes difficult to obtain sufficient atomization performance.

Further, preferably, the bending degree coefficient of the pores of the porous ceramic substrate is 2.0 or less. As a result, the porous ceramic heating element is provided with pores having small bending, so that high atomization performance can be obtained. If the bending coefficient exceeds 2.0, the infiltration resistance of the atomized liquid may increase and the infiltration of the atomized liquid may be insufficient, making it difficult to obtain sufficient atomization performance.

The porous ceramic substrate has an average pore diameter of 0.15 to 72 μm. This facilitates the infiltration of the atomized liquid into the porous ceramic substrate by the capillary action, so that the evaporation efficiency of the atomized liquid, that is, the atomization performance is improved. When the average pore diameter is less than 0.15 nm, the infiltration resistance of the atomized liquid increases and the infiltration of the atomized liquid becomes insufficient, and when the average pore diameter exceeds 72 μm, the capillary force due to the capillary phenomenon decreases. The infiltration of the atomized liquid may be insufficient, and it becomes difficult to obtain sufficient atomization performance.

Further, preferably, the glass layer has a thickness of 3 to 90 μm. When the thickness of the glass layer is less than 3 μm, the resistance value of the resistor pattern varies and the manufacturing yield decreases, and when it exceeds 90 μm, the heat conduction from the resistor pattern to the porous ceramic substrate decreases and atomization occurs. It becomes difficult to obtain sufficient performance.

Further, preferably, the glass layer is composed of a sintered body of a thick film glass paste fixed on one surface of the porous ceramic substrate, and the resistor pattern is fixed on the glass layer. It is composed of a sintered body of a thick film resistor paste, and the electrode pattern is composed of a sintered body of a thick film conductive paste fixed on the glass layer. As a result, since the glass layer and the resistor pattern and the electrode pattern on the glass layer are formed by the thick film on one surface of the porous ceramic substrate, thermal shock resistance and adhesive strength can be obtained. At the same time, durability is obtained.

Further, preferably, the porous ceramic substrate contains any one of alumina, zirconia, mullite, silica, titania, silicon nitride, silicon carbide, and carbon as a main component, and the resistor pattern is silver. It is a thick film sintered body containing metal powder of any one of palladium and ruthenium oxide and glass, and the electrode pattern is made of metal powder of any one of copper, nickel, aluminum, silver, platinum and gold. It is a thick film sintered body containing glass, and the glass layer is a thick film sintered body containing any one of Ba, B, and Zn. As described above, since the glass layer and the resistor pattern and the electrode pattern on the glass layer are formed by the thick film sintered body on one surface of the porous ceramic substrate, the heat impact resistance and adhesion are formed. Strength is obtained and durability is obtained.

Further, preferably, one surface of the porous ceramic substrate is a surface having a longitudinal shape, the pair of electrode patterns are arranged at both ends of the surface having the longitudinal shape, and the resistor patterns are paired. One end of the U-shaped portion is connected to each other and the other end is connected to each of the pair of electrode patterns. As described above, the resistor pattern has a shape in which one end of the pair of U-shaped portions is connected to each other and the tip extending in an arc shape from the other end is connected to each of the pair of electrode patterns. Since heat is not locally concentrated and the entire resistor pattern generates heat uniformly, the evaporation efficiency of the atomized liquid, that is, the atomization performance is improved.

It is a top view of the porous ceramic heating element which is an Example of this invention. It is a process diagram explaining the main part of the manufacturing process of the porous ceramic heating element of FIG. The present invention relates to a test product in which any one of the pore ratio, the average pore diameter, the thickness of the glass layer, the area of the resistor pattern, the thickness of the resistor pattern, the resistance value of the resistor pattern, and the area of the electrode pattern is changed. It is a chart which shows the content and the experimental result of the test product used for the atomization experiment performed by the person, etc. It is a figure which shows the content and the experimental result of the test product used in the atomization experiment performed by the present inventors, etc. for the test product in which the width of the glass layer and the width with respect to the resistor pattern are matched. It is a graph which shows the relationship between the porosity and the atomization amount, which was derived from the data shown in FIG. It is a graph which shows the relationship between the bending degree coefficient and the atomization amount, which was derived from the data shown in FIG. It is a graph which shows the relationship between the porosity bending degree coefficient ratio and the atomization amount, which was derived from the data shown in FIG.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In the following examples, the drawings are appropriately simplified or modified, and the dimensional ratios and shapes of each part are not always drawn accurately.

FIG. 1 is a plan view showing a porous ceramic heating element 10 to which an embodiment of the present invention is applied. The porous ceramic heating element 10 is, for example, one of a rectangular parallelepiped porous ceramic substrate 12 having a long side of 6.0 mm, a short side of 3.0 mm, and a thickness of 3.0 mm, and the porous ceramic substrate 12. The glass layer 16 fixed to the heating surface 12a, which is the surface (upper surface) of the above surface and functions as a heating surface, and the resistor pattern 18 and the electrode pattern 20 fixed to the glass layer 16 by sintering, respectively. It is equipped with. The heat generating surface 12a of the porous ceramic substrate 12 has a rectangular shape and functions as an evaporation surface of a predetermined liquid that has penetrated into the porous ceramic heating element 10 by a capillary phenomenon.

The porous ceramic substrate 12 contains any one of alumina, zirconia, mulite, silica, titania, silicon nitride, silicon carbide, and carbon as a main component, and has an average diameter of, for example, 0.15 to 500 μm, preferably 1.5 to 72 μm. A porous inorganic sintered body having continuous ventilation holes having a pore diameter, for example, a porosity bending degree coefficient ratio (porosity / bending degree coefficient) of 21 or more, preferably 26 or more, and, for example, 30 to 90% by volume. , Preferably it has an average porosity of 40-71% by volume.

The glass layer 16 is made of glass containing Ba, B, Zn, and Si, for example, borosilicate glass, and has a softening point lower than the firing temperature of the porous ceramic substrate 12 and equal to or higher than the firing temperature of the resistor pattern 18 and the electrode pattern 20. Has. The glass layer 16 is a dense glass film fixed to the heat generating surface 12a of the porous ceramic substrate 12 by sintering with a thickness of, for example, 100 μm or less, preferably about 3.0 to 90 μm. The glass layer 16 is formed of the same pattern as or slightly larger than the resistor pattern 18 and the electrode pattern 20 described later, and has substantially the same area as the resistor pattern 18 and the electrode pattern 20.

The resistor pattern 18 has a thickness of 8 to 21 μm and 1 to 3 Ω by bonding metal powders such as silver, palladium, and ruthenium oxide with a thick glass having a melting point equal to or lower than the thick film firing temperature described later. It is a heating element preferably having a value of about 1.1 to 2.7 Ω, and has a thickness fixed by sintering in an S-shaped pattern on the glass layer 16 on the heat generating surface 12a of the porous ceramic substrate 12. It is a membrane resistor. The resistor pattern 18 has an S-shape in which one ends of a pair of U-shaped portions are connected to each other. The resistor pattern 18 is formed on the heat generating surface 12a of the porous ceramic substrate 12 so as to have a size of 5 to 30%, preferably 13 to 21% with respect to the entire heat generating surface 12a.

The pair of electrode patterns 20 have the same conductivity as a conductor by bonding metal powders such as aluminum, nickel, copper, silver, platinum, and gold with a thick film glass having a melting point equal to or lower than the thick film firing temperature described later. It is a thick-film conductor that is rectangular and fixed on the glass layer 16 by sintering at both ends of the heat generating surface 12a of the porous ceramic substrate 12. The pair of electrode patterns 20 are connected to the resistor pattern 18 by overlapping the tips extending in an arc shape from the other end of the pair of U-shaped portions toward the electrode pattern 20 side. The pair of electrode patterns 20 are formed on the heat generating surface 12a of the porous ceramic substrate 12 so as to have a size of 5 to 20% with respect to the entire heat generating surface 12a.

FIG. 2 shows a manufacturing process of the porous ceramic heating element 10. In FIG. 2, in the kneading step P1, the material of the porous ceramic substrate 12, such as alumina powder, inorganic binder, foaming agent, organic binder, water, wax, etc., has a predetermined porosity of, for example, 30 to 90%. After being prepared and mixed at a predetermined mixing ratio so as to be, the mixture is kneaded using a kneader to obtain a clay-like embryo soil. The foaming agent is, for example, resin beads. Next, in the extrusion molding step P2, the embryo soil is molded into a plate-shaped green sheet having a predetermined thickness of about 4 mm using a vacuum extrusion molding machine. Further, a groove for division is formed by pressing a linear blade against this green sheet.

Next, the green sheet obtained in the extrusion molding step P2 is dried in the drying step P3 and then fired in the firing step P4 at a firing temperature of, for example, 1300 ° C to 1500 ° C. As a result, the foaming agent, organic binder, water, wax, etc. in the embryo soil disappear, and at the same time, the alumina particles are bonded by the inorganic binder to form a ceramic plate to which a plurality of porous ceramic substrates 12 are connected. can get.

Next, in the glass paste printing / firing step P5, a thick film glass paste containing, for example, borosilicate glass powder, a resin binder, an organic solvent, etc. is obtained in the firing step P4 in the pattern of the glass layer 16 shown in FIG. After being screen-printed on a plurality of places on the ceramic plate, it is fired at a temperature lower than the firing temperature of the ceramic plate, for example, 800 ° C. to 1000 ° C. As a result, the resin binder, the organic solvent, and the like in the thick-film glass paste disappear, and at the same time, the borosilicate glass melts, and the glass layer 16 is fixed to the ceramic plate by sintering.

In the subsequent electrode paste printing / firing step P6, a thick film electrode paste containing, for example, silver (Ag) powder, a small amount of borosilicate glass, a resin binder, an organic solvent, etc. is fired in the pattern of the electrode pattern 20 shown in FIG. After screen printing on the glass layers 16 at a plurality of locations on the ceramic plate obtained in step P4, a thick film having a firing temperature of, for example, 700 ° C. to 900 ° C., which is the same as or lower than the firing temperature of the glass layer 16. It is fired at the firing temperature. As a result, the resin binder, the organic solvent, etc. in the electrode paste, that is, the conductor paste disappear, and at the same time, the borosilicate glass is melted, and the silver powder is bonded by the melted borosilicate glass, so that the electrode pattern 20 is formed on the ceramic plate. It is fixed on the glass layer 16 of the above by sintering.

Subsequently, in the resistance paste printing / firing step P7, a thick film resistance containing, for example, silver-palladium (Ag-Pd) powder, borosilicate glass, a resin binder, an organic solvent, etc., and having a sheet resistance of, for example, 100 to 200 mΩ / □. The body paste is the pattern of the resistor pattern 18 shown in FIG. 1, and is screen-printed on the glass layer 16 and the electrode pattern 20 at a plurality of locations on the ceramic plate obtained in the firing step P4, respectively, and then the glass layer. It is fired at a firing temperature lower than the firing temperature of 16, for example, a thick film firing temperature of 700 ° C. to 900 ° C. As a result, the resin binder, the organic solvent, etc. in the thick film resistor paste disappear, and at the same time, the borosilicate glass is melted, and the silver-palladium powder is bonded by the melted borosilicate glass, whereby the resistor pattern 18 is formed. It is fixed by sintering on the glass layer 16 and the electrode pattern 20 on the ceramic plate. The resistor pattern 18 may be formed by simultaneous firing with the electrode pattern 20.

Then, in the division step P8, the ceramic plate to which the glass layer 16, the resistor pattern 18 and the electrode pattern 20 are fixed at a plurality of locations is broken along the groove for division, whereby a plurality of porous surfaces are formed. A ceramic heating element 10 is obtained.

The following are the contents of Comparative Example Products 1, 2, 9 and Example Products 1 to 9, which are test samples prepared by the present inventors in the same process as the process shown in FIG. 2, and the experimental results thereof. Will be described with reference to FIGS. 3, 4, and 5.

(Comparative example product 1)
An electrode pattern having an area of 13% with respect to the heat generating surface and 10 μm via a glass layer having a thickness of 20 μm on a non-conductive alumina substrate made of an alumina compact having a pore ratio of 0% by volume. A resistor pattern having a thickness of 2Ω and a resistance value of 2Ω and an area of 15% with respect to the heat generating surface is formed in the same manner as that shown in FIG. I prepared 1.

(Comparative example products 2a and 2b)
A glass layer is placed on two types of substrates, a conductive porous ceramic substrate having an average pore diameter of 3.3 μm and a porosity of 65% by volume, and a non-conductive porous ceramic substrate. FIG. 1 shows an electrode pattern having an area of 13% with respect to the heat generating surface and a resistor pattern having a thickness of 10 μm and a resistance value of 2 Ω and an area of 15% with respect to the heat generating surface 12a. It was formed in the same manner as shown, and two types of comparative example products 2a and 2b were prepared as shown in FIG.

(Example product 1)
On a non-conductive porous ceramic substrate with a porosity of 65% by volume and an average pore diameter of 3.3μm, through a glass layer having a thickness of 20μm, 13% with respect to the heat generating surface. An electrode pattern having an area, a resistor pattern having a thickness of 10 μm and a resistance value of 2 Ω and an area of 15% with respect to the heat generating surface were formed in the same manner as shown in FIG. I prepared it.

(Example products 2a, 2b, 2c)
Glass with a thickness of 20 μm on three non-conductive porous ceramic substrates with porosities of 65% by volume, 60% by volume, and 57% by volume and an average pore diameter of 1.5 μm. FIG. 1 shows an electrode pattern having an area of 13% with respect to the heat generating surface and a resistor pattern having a thickness of 10 μm and a resistance value of 2 Ω and an area of 15% with respect to the heat generating surface via the layer. They were formed in the same manner as shown, and three types of Example products 2a, 2b, and 2c were prepared as shown in FIG.

(Example products 3a, 1, 3b, 3c, 3d, 3e)
Six types of non-conductive porous ceramic substrates with an average pore diameter of 1.5 μm, 3.3 μm, 4.2 μm, 5.1 μm, 72 μm and 0.15 μm and a porosity of 65% by volume. Above, a resistor pattern having a thickness of 10 μm and a resistance value of 2Ω or 1.3Ω and an area of 15% with respect to the heat generating surface is shown in FIG. 1 via a glass layer 16 having a thickness of 20 μm. Six types of Example products 3a, 1, 3b, 3c, 3d, and 3e were prepared as shown in FIG.

(Example products 4a, 1, 4b, 4c, 4d, 4e)
Six types with thicknesses of 22 μm, 20 μm, 19 μm, 17 μm, 90 μm, and 3 μm on a non-conductive porous ceramic substrate with a porosity of 65% by volume and an average pore diameter of 3.3 μm. FIG. 1 shows an electrode pattern having an area of 13% with respect to the heat generating surface and a resistor pattern having a thickness of 10 μm and a resistance value of 2 Ω and an area of 15% with respect to the heat generating surface via the glass layer. 6 types of Example products 4a, 1, 4b, 4c, 4d, and 4e were prepared as shown in FIG.

(Example products 5a, 5b, 5c)
On a non-conductive porous ceramic substrate with a porosity of 65% by volume and an average pore diameter of 3.3μm, through a glass layer having a thickness of 20μm, 13% with respect to the heat generating surface. FIG. 1 shows an area electrode pattern and three types of resistor patterns having a thickness of 8 μm, 17 μm, and a thickness of 21 μm and a resistance value of 1.5 Ω, and having an area of 15% with respect to the heat generating surface 12a. They were formed in the same manner as those of the same ones, and three kinds of Example products 5a, 5b, and 5c were prepared as shown in FIG.

(Example products 6a, 6b, 6c)
On a non-conductive porous ceramic substrate with a porosity of 65% by volume and an average pore diameter of 3.3 μm, through a glass layer with a thickness of 20 μm, a thickness of 17 μm and 1.5 Ω, Three types of resistor patterns with resistance values of 2Ω and 2.7Ω are formed in the same manner as shown in FIG. 1, respectively, and as shown in FIG. 3, three types of Examples 6a, 6b, and 6b are formed. 6c was prepared.

(Example products 7a, 7b, 7c, 7d, 7e, 7f, 7g)
On a non-conductive porous ceramic substrate with a porosity of 65% by volume and an average pore diameter of 3.3 μm, the thickness of 20 μm and the ratio to the width of the resistor pattern are 133%, 167%, 200. A resistor pattern with a thickness of 10 μm and a resistance value of 1.3 Ω is shown in FIG. They were formed in the same manner as shown, and 7 kinds of Example products 7a, 7b, 7c, 7d, 7e, 7f, and 7g were prepared as shown in FIG.

(Example product 8)
An area of 13% with respect to the heat generating surface via a glass layer having a thickness of 20 μm on a conductive porous ceramic substrate having a porosity of 65% by volume and an average pore diameter of 3.3 μm. An electrode pattern and a resistor pattern having a thickness of 10 μm and a resistance value of 2 Ω and an area of 15% with respect to the heat generating surface are formed in the same manner as shown in FIG. 1, as shown in FIG. One type of Example product 8 was prepared in 1.

(Example products 9a, 9b, 9c, 9d, 9e, and comparative example product 9)
Porosity and average fineness of 66% by volume and 26 μm, 40% by volume and 9.8 μm, 65% by volume and 4.0 μm, 66% by volume and 4.1 μm, 71% by volume and 13 μm, 38% by volume and 1.1 μm. A thickness of 10 μm and 1.3 Ω, 1.1 Ω via a glass layer having a thickness of 20 μm and a width of 133% with respect to the electrode pattern, respectively, on a porous ceramic substrate having a pore diameter and no conductivity. , 1.4Ω, 1.4Ω, 1.3Ω, and 1.4Ω, respectively, and 6 types of resistor patterns are formed in the same manner as shown in FIG. 1, and 5 as shown in FIG. Kind of Example product 9a, 9b, 9c, 9d, 9e, and Comparative Example product 9 were prepared.

(Measurement of glass layer thickness)
The cross-sectional shape (profile) of the glass layer 16 in the width direction is measured using a laser microscope, and the average height difference between the cross-sectional shape and the surface of the porous ceramic substrate 12 at 50% of the central portion with respect to the total width dimension is determined by the glass. Calculated as the thickness of the layer.

(Measurement of atomization characteristics)
Atomized liquid: glycerin 45%, propylene glycol 45%
Measurement method of 10% distilled water mixture: The bottom surface of each test product is brought into contact with cotton impregnated with atomized liquid, and in this state, a voltage is applied between a pair of electrode patterns for 3 seconds and 27 seconds. When 21 joules of electrical energy is applied to the resistor pattern in one heating cycle with a voltage application pause period to evaporate the atomized liquid from the upper surface of the heating element, and atomization is performed in five heating cycles. The amount of weight loss of cotton is measured, and the amount of weight loss per heating cycle, that is, the amount of atomization is calculated.

(Durability evaluation method)
After repeating the heating cycle performed in the measurement of the atomization characteristics 100 times, the presence or absence of peeling of the glass layer, the resistor pattern, and the electrode pattern on the porous ceramic substrate is inspected using an 80x stereomicroscope. The presence or absence of peeling was judged, and those without peeling were evaluated as ◯, and those with peeling were evaluated as ×.

(Measurement of porosity)
The porosity of the ceramic substrate was measured by the Archimedes method. After measuring the _{satiety weight as Waw, the dry weight as War, and the underwater weight as Waq , the} porosity P is calculated by substituting them from the following equation (1) representing the porosity P.

(Measurement of stomatal tortuosity coefficient)
Measurement method: The pore volume V, total pore volume V _CO , pore diameter r, and bulk density ρ _Hg of each test product (porous ceramic substrate) are measured using a mercury porosimeter, and the BET specific surface area S is adsorbed. The specific surface area of the test product is calculated based on the adsorption amount of the gas molecule whose occupied area is known, and the measurement is performed using the gas adsorption method, and the bending degree coefficient τ is calculated based on them according to the following equation (2).

In FIGS. 3 and 4, the porosity of the porous ceramic substrate is within the range that satisfies both the criteria required for the product, for example, the atomization amount of 3 mg or more and the absence of peeling in 100 heating cycles. 40 to 71 volume%, average pore diameter of the porous ceramic substrate is 0.15 to 72 μm, the ratio of the width of the glass layer to the width dimension of the resistor pattern is 100 to 300%, and the thickness of the glass layer is 3.0 to 90 μm. Met.

Further, from the data shown in FIG. 4, as shown in FIGS. 5 and 6, the relationship between the atomization amount and the porosity and the relationship between the atomization amount and the tortuosity coefficient are closely correlated with each other. was gotten. In addition, according to FIG. 6, it was shown that in the region where the bending degree coefficient is 2.0 or less, a high atomization amount of 3.0 mg or more, which exceeds the standard 2.5 mg of atomization amount, can be obtained. Further, as shown in FIG. 7, a close correlation was obtained between the amount of atomization and the porosity bending degree coefficient ratio (porosity / bending degree coefficient). When the standard of the atomization amount required for the product is 2.5 mg or more, if the porosity bending degree coefficient ratio is 19 or more, the standard of the atomization amount is satisfied. Further, when the standard of the atomization amount required for the product is 3 mg or more, if the porosity bending degree coefficient ratio is 21 or more, the standard of the atomization amount is satisfied. Further, preferably, the porosity bending degree coefficient ratio is 26 or more.

As described above, according to the porous ceramic heating element 10 of this embodiment, the resistor pattern 18 is fixed on the glass layer 16, and the glass layer 16 and the pair of electrode patterns 20 overlapping the resistor pattern 18 are formed. A porous ceramic heating element 10 that is fixed on the heating surface 12a of the porous ceramic substrate 12 and generates heat by the resistor pattern 18 when a current is supplied between the pair of electrode patterns 20. The pore ratio bending degree coefficient ratio of 12 is 21 or more, and the glass layer 16 is fixed to at least the surface below the resistance pattern 18 among the heat generating surfaces of the porous ceramic substrate 12, and the porous ceramic substrate 12 is fixed. The atomizing liquid that has penetrated into 12 is atomized from the surface of the heating surface 12a of the porous ceramic substrate 12 that is not covered by the glass layer 16 by heating the resistor pattern 18. Therefore, since the porous ceramic substrate 12 does not require conductivity, there are no restrictions on the material, and the material selectivity of the substrate is high. Further, by selecting the porous ceramic substrate material according to the application, it is possible to achieve both chemical resistance to atomized liquid and mechanical strength. Further, the resistance pattern is formed on the heat generation surface 12a, which is one surface of the porous ceramic substrate 12, via the glass layer 16 formed in a part of the heat generation surface 12a including at least the resistance pattern 18. Since the 18 is fixed, the resistance thermometer and the adhesive strength of the resistor pattern 18 functioning as an electric resistance heating element can be obtained, and high evaporation efficiency and durability can be obtained.

According to the porous ceramic heating element 10 of this embodiment, the porosity bending degree coefficient ratio of the porous ceramic substrate 12 is 26 or more. As a result, the porous ceramic substrate 12 is provided with pores having a high porosity and small bending, so that high atomization performance can be obtained. When the porosity bending degree coefficient ratio is less than 26, the porosity may be too low or the pores may be bent too much and the atomized liquid may not be sufficiently infiltrated, so that the atomization performance cannot be sufficiently obtained. There is.

Further, according to the porous ceramic heating element 10 of this embodiment, the porous ceramic substrate 12 has an average porosity of 40% by volume or more and 71% by volume or less. This facilitates the infiltration of the atomized liquid into the porous ceramic substrate 12, so that the evaporation efficiency of the atomized liquid, that is, the atomization performance is improved. If the porosity of the porous ceramic substrate 12 exceeds 70% by volume, the durability of the porous ceramic heating element 10 may not be sufficiently obtained due to peeling of the glass layer 16, the resistor pattern 18, or the electrode pattern 20. .. If the porosity is less than 41.5% by volume, sufficient atomization performance may not be obtained.

According to the porous ceramic heating element 10 of this embodiment, the bending degree coefficient of the pores of the porous ceramic substrate 12 is 2.0 or less. As a result, the porous ceramic heating element 10 is provided with pores having small bending, so that high atomization performance can be obtained. If the bending coefficient exceeds 2.0, the infiltration resistance of the atomized liquid increases, the infiltration of the atomized liquid becomes insufficient, and the atomization performance may not be sufficiently obtained.

According to the porous ceramic heating element 10 of this embodiment, the porous ceramic substrate 12 has an average pore diameter of 0.15 or more and 72 μm or less. As a result, the atomized liquid can be easily infiltrated into the porous ceramic substrate 12 by the capillary action, so that the evaporation efficiency of the atomized liquid, that is, the atomization performance is improved. If the average pore diameter is less than 0.15 μm, the infiltration resistance of the atomized liquid may increase and the infiltration of the atomized liquid may be insufficient. If the average pore diameter exceeds 72 μm, the capillary force due to capillarity may occur. May be reduced and the infiltration of the atomized liquid may be insufficient, and the atomization performance may not be sufficiently obtained.

According to the porous ceramic heating element 10 of this embodiment, the glass layer 16 has a thickness of 3 to 90 μm, preferably 17 or more and 22 μm or less. When the thickness of the glass layer 16 is less than 3 μm, preferably 17 μm, the resistance value of the resistor pattern varies and the manufacturing yield decreases, and when it exceeds 90 μm, preferably 22 μm, the resistance pattern 18 to be a porous ceramic. The heat conduction to the substrate 12 may decrease, and the atomization performance may not be sufficiently obtained.

According to the porous ceramic heating element 10 of this embodiment, the glass layer 16 is made of a sintered body of a thick glass paste fixed on the heating surface 12a, which is one surface of the porous ceramic substrate 12, and has resistance. The body pattern 18 is made of a sintered body of a thick film resistor paste fixed on the glass layer 16, and the electrode pattern 20 is a sintered body of a thick film conductive paste fixed on the glass layer 16. Consists of. As a result, the glass layer 16 and the resistor pattern 18 and the electrode pattern 20 on the glass layer 16 are formed by a thick film on one surface of the porous ceramic substrate 12, so that the heat impact resistance and adhesion are obtained. Strength is obtained and durability is obtained.

According to the porous ceramic heating element 10 of this embodiment, the porous ceramic substrate 12 contains any one of alumina, zirconia, mulite, silica, titania, silicon nitride, silicon carbide, and carbon as a main component. The resistor pattern 18 is a thick film sintered body containing a metal powder of any one of silver, palladium and ruthenium oxide and glass, and the electrode pattern 20 is made of copper, nickel, aluminum, silver, platinum and gold. It is a thick film sintered body containing any one of the metal powders and glass, and the glass layer 16 is a thick film sintered body containing any one of Ba, B, and Zn. As described above, the glass layer 16 and the resistor pattern 18 and the electrode pattern 20 on the glass layer 16 are formed by the thick film sintered body on the heat generating surface 12a which is one surface of the porous ceramic substrate 12. Therefore, thermal shock resistance and adhesive strength can be obtained, and durability can be obtained.

According to the porous ceramic heating element 10 of this embodiment, one surface of the porous ceramic substrate 12 is a heat generating surface 12a, which is a surface having a longitudinal shape, and the pair of electrode patterns 20 are surfaces having a longitudinal shape. Arranged at both ends, the resistor pattern 18 has a pair of electrode patterns 20 having one end of a pair of U-shaped portions connected to each other and an arc extending from the other end toward the electrode pattern 20. It is connected. As described above, since the resistor pattern 18 has a shape in which one end of the pair of U-shaped portions is connected to each other and the other end is connected to each of the pair of electrode patterns 20, heat is locally concentrated. Instead, the entire resistor pattern 18 generates heat uniformly, so that the evaporation efficiency of the atomized liquid, that is, the atomization performance is improved.

Although the preferred embodiments of the present invention have been described in detail with reference to the drawings, the present invention is not limited to this, and the present invention is also carried out in still another embodiment.

For example, in the above-mentioned embodiment, the atomized liquid was a mixed liquid having a ratio of glycerin, propylene glycol, and distilled water in a ratio of 5: 5: 1, but other ratios may be used, such as fragrances and the like. The liquid may be further added.

Further, in the above-described embodiment, the resistor pattern 18 has a resistance value of about 1Ω or more and 3Ω or less, but may be changed to another resistance value in relation to power transmission or the like.

Further, although the resistor pattern 18 of the above-described embodiment is an S-shaped pattern, it may be a pattern having another shape such as a sinusoidal pattern or a rectangular pattern.

Further, in the above-described embodiment, the glass layer 16 is formed of the same pattern as the resistor pattern 18 and the electrode pattern 20 or a slightly larger pattern, but is not necessarily the same pattern as the resistor pattern 18 and the electrode pattern 20. The pattern may be larger and different from the resistor pattern 18 and the electrode pattern 20 as long as the atomizing performance for atomizing the atomizing liquid is satisfied and the resistor pattern 18 can be supported.

Further, although the pair of electrode patterns 20 are formed on the glass layer 16 at both ends of the heat generating surface 12a of the porous ceramic substrate 12, they do not necessarily have to be both ends. Further, the electrode pattern 20 does not necessarily have to be formed on the glass layer 16.

Further, in the above-described embodiment, the glass layer 16, the resistor pattern 18, and the electrode pattern 20 are made of a thick film on the heat generating surface 12a of the porous ceramic substrate 12, but the resistor pattern 18 and the electrode pattern 20 are formed. At least one of the above may be composed of a thin film using sputtering.

In addition, although not illustrated one by one, the present invention is carried out with various modifications within a range not deviating from the gist thereof.

10: Porous ceramic heating element 12: Porous ceramic substrate 12a: Heat generating surface (one surface of the porous ceramic substrate)
16: Glass layer 18: Resistor pattern 20: Electrode pattern

Claims (9)

The resistor pattern and the pair of electrode patterns overlapping the resistor pattern are fixed on one surface of the porous ceramic substrate, and a current is supplied between the pair of electrode patterns to generate heat of the resistor pattern. Porous ceramic heating element
The porosity bending degree coefficient ratio of the porous ceramic substrate is 21 or more.
A glass layer is fixed to at least a part of one surface of the porous ceramic substrate including the resistor pattern, and the resistor pattern is fixed on the glass layer.
It is characterized in that the atomized liquid that has penetrated into the porous ceramic substrate is atomized from one surface of the porous ceramic substrate that is not covered with the glass layer by heating the resistor pattern. Porous ceramic heating element. The porous ceramic heating element according to claim 1, wherein the porosity bending degree coefficient ratio of the porous ceramic substrate is 26 or more. The porous ceramic heating element according to claim 1 or 2, wherein the average porosity of the porous ceramic substrate is 40 to 71% by volume. The porous ceramic heating element according to any one of claims 1 to 3, wherein the porosity coefficient of the pores of the porous ceramic substrate is 2.0 or less. The porous ceramic heating element according to any one of claims 1 to 4, wherein the porous ceramic substrate has an average pore diameter of 0.15 to 72 μm. The porous ceramic heating element according to any one of claims 1 to 5, wherein the glass layer has a thickness of 3 to 90 μm. The glass layer is composed of a sintered body of a thick glass paste fixed on one surface of the porous ceramic substrate.
The resistor pattern is composed of a sintered body of a thick film resistor paste fixed on the glass layer.
The porous ceramic heating element according to any one of claims 1 to 6, wherein the electrode pattern is composed of a sintered body of a thick film conductive paste fixed on the glass layer. The porous ceramic substrate contains any one of alumina, zirconia, mullite, silica, titania, silicon nitride, silicon carbide, and carbon as a main component.
The resistor pattern is a thick film sintered body containing a metal powder of any one of silver, palladium, and ruthenium oxide and glass.
The electrode pattern is a thick film sintered body containing a metal powder of any one of copper, nickel, aluminum, silver, platinum, and gold and glass.
The porous ceramic heating element according to claim 7, wherein the glass layer is a thick film sintered body containing any one of Ba, B, and Zn. One surface of the porous ceramic substrate is a surface having a longitudinal shape.
The pair of electrode patterns are arranged at both ends of the surface of the longitudinal shape, and in the resistor pattern, one end of the pair of U-shaped portions is connected to each other and the other end is connected to each of the pair of electrode patterns. The porous ceramic heating element according to any one of claims 1 to 8, wherein the porous ceramic heating element is characterized by the above.

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